1. According to the speaker, what have some called "potentially the most important medical
advance this century"? How does it work?

According to the speaker, the potentially most important medical advance in this century is oral rehydration salts. The sodium and glucose combined, when added to water, makes it so that the child is able to absorb the water during situations of diarrhea.

Explanation:

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The right answer is:

A: The stock market crash caused a panic   >   people rushed to pull money out of the banks   >   Banks did not have enough money for everyone.

Explanation

The aforementioned excerpt is from "American Life Histories: Manuscripts from the Federal Writers' Project, 1936-1940" and it describes a group of men in New York City who made a living by collecting and selling junk from their pushcarts.

It specifically refers to the stock market crash of 1929 during which there was a collapse of stock prices. It was the worst decline in U.S. history.

People were forced to sell businesses and take out their life savings. Unemployment took place later as businesses failed.